Internal combustion engine



FIG. 1 is a front elevational view of the internal combustion engine of the present invention;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is right side elevational view thereof;

FIG. 4is a left side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for an internal combustion engine, as shown and described. 